Molecular characterization of Vibrio cholerae strains from clinical samples during the 2025 epidemic in the Republic of the Congo

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Objective The study aimed to determine the bacteriological and molecular profile of Vibrio cholerae strains responsible for the cholera outbreak of July 2025 in the Republic of Congo. Methods Fecal samples were collected from patients suspected of having cholera and admitted to health centers in four departments of the Republic of Congo (RoC) and sent to the National Public Health Laboratory for analysis. The samples were cultured and the isolates obtained were subjected to serotyping and antibiotic susceptibility tests. Whole genome sequencing was performed using the Illumina DNA Prep kit. Results Of the 57 samples analyzed, 15 were phenotypically positive for Vibrio cholerae O1 Ogawa and were confirmed genotypically. Phylogenetic analysis highlights an epidemic clone showing a link with Nigerian strains. The strains were resistant to ampicillin and nalidixic acid and sensitive to ciprofloxacin and doxycycline. All the strains had the same resistance genes; however, one of them had additional resistance genes. At the same time, the virulence genes ctxA/B, tcpA/B, toxT and zot were identified in all the strains. Conclusion These results reveal the emergence in the Republic of Congo of a virulent and multiresistant strain of Vibrio cholerae O1 Ogawa , similar to Nigerian strains. Its control requires cross-border coordination focused on genomic surveillance and mass vaccination.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.